Tool for inserting and extracting wire coil inserts in and from tapped holes



July 4, 1950 J. o. FORSTER TOOL FOR INSERTING. AND EXTRACTING WIRE COIL INSERTS IN AND FROM TAPPED HOLES Filed Nov. 13. 1946 2/ FIG. I.

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m F 0 W O J "ATTORNIE'IZ Patented July 4, i956 TOOL FOR INSERTING AND EXTRACTING WIRE COIL INSERTS IN AND FROM TAPPED HOLES John 0. Forster, Long Island City, N. Y., assignor' to Heli-Coil Corporation, a corporation of New York Application November 13, 1946, Serial No.- 709,554

6 Claims.

The invention relates to a tool for inserting a wire thread coil in the tapped hole of a boss or nut member as for instance described in U. S. Patent 2,316,231 of April 13, 1943, to Neil Evans. Tools of the type under consideration comprise means causing, before and during the insertion, a contraction of the coils which are usually wound with a diameter larger than that of the tapped holes. For this purpose the conventional device comprises an internally threaded part tapped according to the diameter to which the coil is to be contracted, and a mandrel with the aid of which the coil can be screwed through that threaded part. The invention aims to provide a simplified tool for the indicated purpose. It essentially consists of a mandrel and a, sleeve freely rotatable on the mandrel. The latter has an end slotted to engage and take along an inner end projection such as a diametric tang of the coil, and the sleeve has an inner taper to engage and frictionally restrain the other coil end when the mandrel is turned relatively to the sleeve while the coil is pressed by the sleeve in axial direction against the boss or nut threading. The invention has for another object the provision of means applicable to the inserting tool whereby the latter can be readly converted into an extracting tool.

Further objects and details of the invention will be apparent from the description given herei inafter and the accompanying drawing illustrating an embodiment thereof by way of example.

In the drawing:

Fig. l is a side elevation partly in section of a tool according to the invention,

Fig. 2 is a cross-section along the line 22 of Fig. 1, on a larger scale,

Fig. 3 is a side elevation partly in section of a modified tool with an extracting element attached,

Fig. 4 is a side elevation of the extracting element, and

Fig. 5 is a cross-section along line 55 in Fig. 3.

Referring to the drawing, the tool illustrated in Figs. 1 and 2 comprises a mandrel l0 and a sleeve H. The mandrel substantially consists of a cylindrical rod having a head portion l2 and a portion l3 reduced to a diameter according to the inner diameter to which a wire coil intended to be inserted in a hole is to be contracted. However, it is also possible to use a mandrel having a uniform diameter throughout its length.

The head !2 is provided with means whereby a torque may be applied to the mandrel, be it by hand or in connection with a power drive. Such means consist in the present embodiment of a transverse bore l4 into which a cross bar (not shown) may be inserted. The drawing also dicates an axial square hole [5 into which a square head of a wrench or the like (not shown) may be applied for the same purpose. Either one, bore M or hole l5, will be used at a time. The end of the mandrel opposite the head [2 is slotted at Hi to receive the interiorly projecting tang ll of a wire coil l8 intended to be inserted in the tapped hole l9, which is provided in the face 20 of a boss or nut 2|. The sleeve ll fits on the portion l3 of the mandrel and has an inner tapered shoulder 22 to be engaged by the end 23 of the coil I8 when the tang I! of the latter is in engagement with the slot [6. An outer rim 24 projects in axial direction from shoulder 22, so as to encompass circumferentially the end 23 of the coil when it bears against the shoulder 22 in order to prevent the coil end from slipping outward. The sleeve H is prevented from axial movement on the rod at least beyond a predetermined limit from the inner end 25 of the slot Hi. This may be accomplished by the provision of the shoulder 26 between the mandrel portions I2 and I 3. However it is preferred to prevent the sleeve also from slipping off the slotted mandrel end. For this purpose, the mandrel may be provided With a groove 21 into which a pin or screw 28 inserted in the side wall of the sleeve engages without interfering with a free rotation of the sleeve in relation to the mandrel. If such means are provided the shoulder 26 is unnecessary as the screw 28 in engagement with the groove 21 will prevent axial movement of the sleeve in both directions. For reasons to be explained later, it is advisable to make the slot I6 relatively long; so long in any event that the maximum distance of the slot bottom 25 from the tapered shoulder 22 of sleeve II is shorter than the length of the coil to be inserted bythe tool. Furthermore, it is advisable to provide the slot with two diametrically opposite sharp edges 29 and 30 shown in Fig. 2 in order to cut off a tang after the insertion of the coil, and with two rounded or blunt edges 3| and 32 according to the bent portion 33 between the tang and the adjacent coil convolution.

In using the tool, a coil 18 is slipped on-the mandrel from the side of the slotted end so that the latter is engaged by the coil tang or projection H. In this position and while the end; 23 of the coil lies against'the taper 22, the tool is applied to the hole I9 of the boss 2| whereby the tanged end of the coil comes to bear against the slotted portion of the mandrel '40.

.blade can be so inserted in the slot43 that the 3 surface 20 in which the threaded hole I9 is provided. If, now, mandrel I0 is turned in the direction to screw the coil in while sleeve I I is held non-rotatable and while simultaneously the tool urged towards the boss member, friction is set up between the taper 22 and thecoil-end 23 so that further turning of the mandrel simultaneously contracts the 'coil between its ends and screws the tang coil end into the hole I9. During this operation it is imperative that the tang is not restricted in axial direction, because otherwise, i. e. if for instance the slot bottom presses on the tang, the latter might be .bent out of its plane. This is the reason why the tang should be 'suffi ciently free to move axially in the slot and Why the distance between slot bottom and sleeve taper should be less than the length of the coil. Of course, when the coil is in a sufiiciently contracted state, the sleeve should be retained with sufficient force only to maintain the contracted state of the coil while the coil now may turnsimultaneously with the mandrel. When a few convolutions of the coil have been inserted, no

further retaining force need be applied to the sleeve because :further contraction of the entering coil convolutions will be caused'by the threading of the hole l9.

In order to convert the tool just'described into a coil-extractng tool it is merely necessary to add another element. This is shown in connection with the modified tool illustrated in Figs. 3

to 5. This tool comprises as in the first example a mandrel 40 and a sleeve 4|. The mandrel in this case is shown as astraight rod with a handle 42 and slot 43. The rod is provided with three spaced grooves 44, 45,46 which allow for anadjustment of the sleeve in'thr'ee different positions in order to vary the distance of the slot bottom 47 from the sleeves tapered shoulder 48. According to what has been stated hereinbefore, such adjustability is desirable to render thetool useful for coils of different length. The'sleeve'is grooved at 49 near its end opposite the shoulder rim 5!] and a radial bore 5! is directed from the groove bottom to the interior of the sleeve. An

open spring ring 52 with a radial projection 53 is inserted into the groove and bore so that the projection engages the mandrel groove 44. The ring can bebent Over the rounded end face 54 of the sleeve, to disengage the projection 51 from groove 44 whereupon the sleeve can be shifted axially. :The projection 53 may, then, be brought into en- .gagement with groove 45-or to hold the sleeve .inthe so adjusted position. In all other respects,

mandrel 40- and sleeve 4| are similar to the corresponding parts of Fig. 1, and may be used in the manner described for inserting a Wire coil in a boss or nut. Now, in order to make the tool useful for extraction, a blade 55 is provided, having the shape substantially of an elongated trapezoid. This blade has a thickness fitting into mandrel slot 43. The blade has two sharp edges 56 in diametrical opposition to each other along the converging sides of the trapezoid. Various means may be applied to hold the blade releasably in co-axial relationship to the mandrel 40. Such means consist, in the illustrated embodiment, ofa rectangular recess 51 in the middle of 1 the longer one of the parallel sides of the trapezoid. The width of the recess is equal to the non- Thus the "screwed out, and as the torque acts on the top end of the coil the latter will be contracted during this operation which thereby Will be facilitated.

It will be clear to those skilled in the art that many alterations and modifications of the struc- "ture shown and described are possible without departure fronfthe essence and spirit of the invention which for .this reason shall not be limited but by the scope of the appended claims.

I claim:

1. A tool of the character described comprising a rod-like'member having one end with an elongated slot therein and another end adapted for the application of atorque, a sleeverotatable on said rod, said sleeve having near one'of its 'endsan inner shoulder tapering towards its other end and an axially projecting rim adjacent said shoulder and adapted to receive therein the end of a wire coil bearing on said shoulder, and interengageablemeans in connection with said sleeve and said rod to limit the distance the slotted rod end is projectable from the rim-provided end of said sleeve.

2. A tool as claimedin claim 1, the diameter of the slottedman'drel portion substantially equal to the desired inner diameter of said coil after its contraction, and said rim having an inner diameter substantially correspondin to the outer coil diameter prior to the contraction of the coil for which the tool is destined.

3. A tool as claimed in claim 1 wherein the maximum distance of the slot bottom from the sleeve shoulder is less than the length of the coil vfor which the tool is destined.

4. A tool as claimed in claim 1, further comprising means in engagement with said sleeve and adapted to engage said rod to hold said sleeve on said rod rotatable but nori-sliiftable in axial direction.

5. A tool as claimed .in claim 1, further comprising adjustable means in engagement with said sleeve and adapted to engage said rod for adjusting the axial distance of said sleeve from the slot bottom and to hold it in adjusted position.

6. A tool as claimed in claim 1, further .comprising a substantially trapezoidal, two-edged blade releasablyfitted into said slot and means in connection with said blade-and adap'tedfor engagement with said rod so as to hold said blade in co-axial alignment with said rod and with the narrow blade end projecting from said rod.

JOHN O. FORSTER.

REFERENCES CITED The following references are of record in the idle of this patent:

UNITED STATES PATENPS Hawkins Mar. 20, 1945 

